Laparoscopic and endoscopic surgical methods have become increasingly popular in recent years. Such methods typically involve making small incisions in the abdominal wall of a patient through which specially designed laparoscopic or endoscopic tools are inserted for carrying out the surgical procedure. Such tools typically have a miniaturised surgical implement such as forceps or scissors at the end of a long shaft to the other end of which is attached a handle and actuating mechanism. By the use of such tools, the surgeon can operate the instrument from outside the patient's body whilst monitoring the movement of the surgical tool within the body by means of an endoscope.
Such techniques of minimally invasive therapy (MIT), which have been commonly referred to as keyhole surgery, offer very substantial advantages over conventional open surgery in that only very small incisions in the patient's body wall are required thus substantially minimising patient trauma, dramatically reducing post-operative complications, and greatly reducing the opatient's recovery time.
As laparoscopic or endoscopic surgical techniques are generally more delicate than those of open surgery, the surgical instruments need to be particularly easy in manipulate and use. Hitherto, the surgical instruments used in MIT have been cumbersome to use. For example, many conventional laparoscopic instruments have off-centre scissor handles for actuating the surgical tool. The presence of such scissor-handle actuated mechanisms makes steady control and rotation of the instrument difficult. To overcome this problem, some tools are provided with a thumb wheel by which the actuator shaft is rotated independently from the scissor handles. However, such an arrangement is clumsy to use and often requires two hands to operate effectively. Thus, there remains a need for surgical instruments for use in surgery which are more easily manipulated, can be operated entirely by one hand, can be rotated freely, and operated just as effectively in any rotated position to enable the orientation of the surgical tool to be varied as required. It is an object of the present invention to provide such an instrument.